Molybdenum is extensively employed for producing a variety of molybdenum-base alloys and as an alloying agent in other alloy systems for imparting beneficial mechanical and chemical properties thereto. Conventionally, metallic molybdenum is produced by the reduction of molybdenum oxide derived from the roasting of molybdenite (MoS.sub.2) at an elevated temperature in the presence of excess oxygen. It has been customary, in accordance with prior art practices, to employ a batchwise multiple-step process for effecting a progressive reduction of a relatively high-grade molybdenum oxide feed material to a comparatively pure metallic molybdenum product suitable for use in the preparation of molybdenum catalysts and reagent grade molybdenum chemical compounds. A typical batchwise process of the aforementioned type is described in U.S. Pat. No. 2,398,114.
A common form of molybdenum which is employed extensively in metallurgical operations is the ferro alloy which is universally produced by batch-type operations either employing a thermit process or employing an electric furnace reduction process. Both of the foregoing techniques are labor and energy intensive, with the thermit process, in particular, posing problems due to environmental considerations.
The present invention overcomes the problems and disadvantages associated with batch-type prior art processes providing an efficient continuous process for directly reducing an agglomerated molybdenum oxide feed material to a pelletized substantially metallic molybdenum product which is of excellent quality and of high density, rendering it eminently suitable for use as an alloying addition agent in steelmaking operations and the like.
Prior art attempts to effect a direct reduction of molybdenum oxide to metallic molybdenum on a continuous basis have heretofore been unsuccessful due to the difficulty of controlling the exothermic and endothermic two-stage reduction reactions to avoid the formation of appreciable quantities of volatile molybdenum oxide and/or a sintering of the agglomerated feed material into a nonfriable mass.